Inner ture



Jan. 4,1927, 1,613,089

G. H. ELLINWOOD INNER TUBE Filed Nov 7. 1921 EEDRBE H. ELLINWEIEID' MENTOR ET W A TDRNEY Jim 4,1921.

UNi EnjsTAras PATENT OFFICE.

GEORGE E. EILINWOODQOF MILWAUKEE, WISCONSIN,

ASSIGNOB, BY IJZSNE ASSIGN HINTS, TO FISK RUBBER COMPANY, OF CHICOPEE FALLS, MASSACHUSETTS, A COB- roaarron or uassacnnsa'rrs.

miter. 'ruim.

Application aim November 7, 1921." Serial no. $13,469.

Figure -1 is a section through a raw tube,

Figure 2 is a section through one of the tubes illustrated as embodying my invention, while tially circular mandrel to' thereby cure the tube in substantially the shape in which. it is to be used but it is more economical to cure such tubes on astraight'mandrel andiorm the straight tube intoan annulus after curing. Forming the strai ht tube into] an annulus after curing resultsin producing a relatively different circumferential length in each longitudinal line of the tube and inflation o,

tion of he tube under greater tension t an the inner or rim'portiqn so that inflation relatively elo atesthe outer or tread por tionand there y ness of the tread ;p ,rti'on. On the other hand, this tread portion is the part of the tube which is most sub'ect to puncture and which therefore shoul' normall be of a thickness at least equal to that 0 any other portion. It has been proposed to correct this condition by forming the straight tube of unequal thickness and making that part of the tube which is tobecomei the tread portion of greater thickness than that portion which is to become the rim-portion so that m the inflated tube the tread portion will still be at leastasthick as. the rim portion.

' It has been proposed to thicken the tube in-this manner by tubing it through an eccentric die. In certain cases, however, 1t is more desirable to calender stock and roll the tube than to tube the tube and in such cases the tube cannot be so thickened. I find, however, that the result may be accom- Figure 3 is a; section". through the other" i the tube places the outer tread org reduces the relative thickplished by rolling the stock onto a mandrel in the manner shown in the drawings wherein the sheet is shown as wound one or more tlmes about the mandrel and then continued from the line 11 over the region 12 to the line 13 to thereby add an extra ly over the region 12. When the tube is ormed into the annulus this extra ply supplies suflicient material so that the tread portion of the tube after assuming annular form is still as thick or thicker than the remainder of the tube. Further, with this construction the rim portion, which is subject to pinching and chafing, is then thicker than the side portions which are subject to practically no wear. a

When a tube is used with a clincher tire without aflap, and particularly with a. clincher cord, normal conditions of wear are often reversed and the greatest damage to the tube comes through pinchin and abrasion by the movement of the basis. In such case it may be desirable to thicken the base of the tube so that that part is considerably thicker than the tread portion and therefore heavyenough to prevent pinch' Such a construction is particularly desirable when the tube is already of sufficient general thickness to provide a satisfactory tread portion.

The tube may be thickened at the base by forming the raw tube of excess thickness and this uneven thickness may be secured by either-of the methods above described except that the thickened portion will be placed at the inside of the annulus instead of at the outside. I

I have described herein certain embodiments of my invention but this description is illustrative only and my invention is not limited thereto.

I claim:

, 1. The method of manufacturin calendered inner tubes which com rises ormin the tube. by rolling the ca endered st about a straight mandrel with the stock overlapping that portion which in the finished tube is subject to distortion an amount sufficient to substantially equalize the decrease. in thickness of the tube when the latter is formed into an annulus and inflated when in an uninflated condition, the inand curing the tube while on the straight creased thickness of said portion being such 10 mandrel. that the tube is of uniform thickness 1 2. A vulcanized annular inner tube of unthroughout when in an inflated condition. 5 equal thickness when uninflated and of lini- In testimon whereof I have signed my form thickness when inflated. name to the a ve specification.

3. A vulcanized annular inner tube having a tread portion of increased thickness GEORGE H. ELLINWOOD. 

